PHILADELPHIA (AP) -- Scott Hartnell couldn't hear the referee, so he listened to the fans.
"When I heard the cheers, I knew we won," Hartnell said.
Biron kept the Flyers in it with a pad save on a point-blank shot by Jack Johnson in overtime.
With the clock winding down, Mike Richards dumped the puck toward a streaking Hartnell, who slid toward the net and scored his 17th goal off his skate.
The play was reviewed, but it was determined Hartnell didn't intentionally kick the puck.
"The guy knocked me down, it hit my skate and went in," Hartnell said. "It doesn't matter how pretty they are."
Kings goaltender Jason LaBarbera had trouble seeing the puck with Hartnell crashing toward him.
"It happened so fast. It was tough for me to see," LaBarbera said. "I know it didn't go off [Hartnell's] stick. It just bounced off the ice and hit his shin pad and it went in. Fluke play."
Los Angeles is in the same position the Flyers were in at the end of last season -- dead last in the NHL. But Philadelphia has put together a remarkable turnaround after the worst season in franchise history.
With New Jersey's loss to Pittsburgh, the Flyers are alone in first place in a jumbled division in which seven points separate the five teams.
However, the Flyers have struggled to win in the extra period. Their only other overtime victory in seven tries this season was back on Oct. 20 against Carolina. That final was also 3-2.
"It's nice to finally win one in overtime," Coburn said.
Soon after both teams had shots bounce off the right post early in the third period, a hooking penalty on Jaroslav Modry gave the Flyers a power play.
Gagne put the Flyers ahead 2-1 when he deflected Kimmo Timonen's slap shot past LaBarbera for his seventh goal 3:48 into the final period.
Moulson deflected Lubomir Visnovsky's rising shot from near the blue line over Biron's shoulder to tie it at 2 with 7:02 remaining.
"We got a point out of it in a tough building," Kings coach Marc Crawford said. "It's something we can build on."
After a scoreless first period in the first game following the All-Star break, the teams traded goals in the opening two minutes of the second.
Coburn gave the Flyers a 1-0 lead when he ripped a shot from just inside the blue line through a screen past LaBarbera. The puck appeared to deflect off a Kings defenseman on its way into the net.
Kopitar answered with his 20th goal following a giveaway by Richards along the boards.
The Flyers are 12-2-2 in their last 16 games. ... The Kings opened a season-high eight-game road trip with their first game in Philly since Feb. 20, 2003. ... The Flyers haven't lost to the Kings at home in regulation over their last nine games, going 8-0-1. ... Coburn has a point in five straight games and 23 overall.